The present invention relates to a hydraulic control valve with a control member which is longitudinally displaceable in a longitudinal opening of a housing.
Hydraulic control valves of the above mentioned general type are widely known in the art. One of such hydraulic control valves is formed as a two-step, continuously operating 4/3-directional proportional valve, and its hydraulically actuatable main control slider which serves as a control member is provided with a rotation preventing element. For this purpose, parallel pins are fixedly arranged in the housing and extend in the axial movement direction of the main control sleeve. Both pins are pressed with their end in the housing cover, while the other free end extends in an end-side opening of the main control slider. With this rotation preventing element the diameter of both pins is limited since the end-side piston portion of the main control slider in addition to the guiding openings for the pins, also must receive a head-shaped spring plate, in which additionally the spring for a double-acting return device of the main control slider extends. Moreover, the spring plates must be provided with throughgoing openings for both pins. This rotation preventing element has the disadvantage that it is relatively expensive and also it is subjected to high mechanical loads. The power take-up through axially arranged pins permits the transmission of low moments which during the operation of such valve within the limited region are frequently exceeded. Further, in this rotation preventing element the pins are subjected to different bending loads, depending on the respective position of the slider. In addition, in this torsion safety element the pins must be exactly aligned with the guiding openings for avoiding any interference with the movability of the control slider.
The German document DE-OS 2,031,584 discloses a hydraulic current regulator which has a longitudinally movable control member secured against turning by a longitudinal pin which extends eccentrically to the longitudinal axis. This current regulator deals primarily with a position securing of the control member so as to provide that the control openings in the longitudinally movable control member are guided relative to the housing-fixed control openings always in the same turning position. Also, this rotation preventing element has substantially the same disadvantages as the above described rotation preventing element with axial force take up and is not suitable for directional valves which have control sliders deflectable in different working positions against a double-acting return unit.
The German document DE-OS 2,658,928 shows in FIG. 7a a hydraulic volume stream sensor with a control member which is deflectable from a spring-centered central position to both sides in working positions. For facilitating the pick-up of an electrical control signal, the longitudinally movable control member is secured against torsion with the help of an eccentric pin which is arranged in the longitudinal direction of the control member in a housing-fixed opening. This rotation preventing element is not suitable for transmitting high moments.